The purpose of this project is to investigate the dynamic function of the cardiac valves in order to understand (1) how the valves can function so efficiently and (2) how alterations in cardiac rhythm and function can effect the ability of the valves to maintain a largely unidirectional blood flow. By using a unique new high-speed cineradiographic technique the motion of the valve annuli and leaflets will be tracked throughout the cardiac circle. The patterns of valve motion, the leaflet velocity, the leaflet acceleration and the temporal relationship between valvular motion and other cardiac events such as the generation of the heart sounds, atrial systole, ventricular systole and the end of ventricular filling will be examined. Because of the suspected relationship between retro-leaflet vortices and valve closure the three dimensional pattern of blood flow around the valves will be studied quantitatively by using biplane cineradiography to trace small radiopaque particles as they are being carried by the blood. The complete understanding of normal valvular function will aid in understanding valvular function altered by cardiac arrhythmias, reduced ventricular function, and rheumatic heart disease. Also this radiographic technique may aid in the interpretation of data obtained from the application of ultrasound to the study of valvular function.